How can I change "ADC Sample Rate" of AD9680 on FMCDAQ2

Question

Hello. 
 
 I'm using the AD-FMCDAQ2-EBZ module for utilizing the ADC (AD9680). 
 The sample rate of ADC was set 1000 MSPS automatically. 
 
 I want to change the ADC sample rate to 998MSPS or 997MSPS. 
 But I don't know whether it is possible or not. 
 
 Please let me know how to change the ADC sample rate. 
 Thanks.

PaulPG · Accepted Answer

Hi Riache, 
 The method you used is not appropriate in this case because the software will still read 1000 samples. 
 One method to test the sample rate is: 1. Take an external signal generator. 2. Connect it to a RX channel. 4. Plot the frequency domain characteristics. 3. Read the harmonic frequency(using Peak Markers). 4. Modify the clock generator parameters according to the previous answer. 5. Plot the frequency domain characteristics again. 6. Read the harmonic frequency and you will find a different value, which means that the value of the sampling rate has changed. If you want this test to be performed without an external source or to be performed with the IIO Oscilloscope software, then you will need to change the clock generator instantiation parameters in the devicetree(.dtsi) file. 
 Here you can find the .dtsi file for arm architecture or arm64 architecture . 
 I will modify this file and test the 995 MHz sampling rate and come back with a response. 
 Thank, Paul)

PaulPG · Answer

Hi Riache, 
 Yes, it is possible to change the parameters from the fmcdaq2.c file. In this case, if you change the parameters you highlighted and choose the profile in which the sample rate for the ADC and DAC is 1GSPS you should see in the IIO Oscilloscope a 995 MHz sampling frequency. 
 I modified the parameters highlighted below and obtained using the .csv data method 995 samples for 1 &mu;s and the sampling frequency as in the picture below. 
 
 Thanks, 
 Paul

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How can I change "ADC Sample Rate" of AD9680 on FMCDAQ2